The present invention relates to compositions and methods to allow wet-cleaning, including oil stain removal, and subsequently drying in a tumbler dryer, of sensitive garments and other fabrics made of water-sensitive protein fibers such as wool, cashmere or silk without any dimensional changes, surface damages and dye or color loss. These compositions and methods can be applied in a professional or household cleaning process.
Sensitive garments and other fabrics may be cleaned and dried in a variety of manners using professional wet or dry cleaning processes or modern household laundry equipment. Sensitive items including garments and fabrics made of hair, silk, rayon, animal hair, animal skin and mixed spun materials, have a tendency to shrink when they are washed in water. In order to avoid shrinkage caused by washing in water, many of these sensitive garments and fabrics are conventionally dry cleaned.
Dry Cleaning
By definition, the term “dry cleaning” has been used to describe processes for cleaning textiles using non-aqueous solvents. Dry cleaning is an old art first discovered in the mid-19th century when potential to use petroleum-based solvents to remove grease, wax and oil-based stains from textiles was discovered. Solvent cleaning was first recorded in the United Kingdom in the 1860s with gasoline and kerosene as first solvents used.
Chlorinated solvents were introduced after World War I; since the mid-1930s the most commonly used solvent has been tetrachloroethylene, also called perchloroethylene which has the advantage of being stable, non flammable, and having better cleaning capabilities than aqueous solvents for removal of oil-based stains. Since that time most fabrics having a tendency to shrink by contact of water, or which are judged to be too valuable or delicate to be subjected to aqueous laundering processes, are dry cleaned.
While perchloroethylene is superior to the non-aqueous solvents that it replaced, it has several disadvantages. Particularly, perchloroethylene has been identified as a hazardous air and ground water pollutant (listed as such under the Clean Air Act by the U.S. Environmental Protection Agency and declared as a toxic chemical by California in 1991); it has been also long associated with nervous-system, severe skin irritation, liver and kidney disorders amongst industrial workers and listed as probable carcinogen by the International Agency for Research on Cancer (IARC) in 1995. Recent studies revealed that perchloroethylene's potential carcinogenic effects are not limited solely to industrial workers or those who operate dry clean processes; some commercial dry cleaners used such high amounts of perchloroethylene to clean garments, that customers who wore freshly dry-cleaned garments could inhale enough perchloroethylene to incur a slightly increased risk of cancer. Perchloroethylene will become illegal in California in 2023.
As a consequence of this hazardous nature of perchloroethylene, processes utilizing it must be done at commercial establishments. Traditional dry cleaning involves solvent-using wash cycle and several filtration steps to recover some of the solvent through filtration units comprising a distillation boiler and condenser. Distilled solvent is recovered during extraction and drying cycles. Dry cleaning produces toxic waste residues that have to be regularly removed by the operator such as solid waste sludge, lint and cartridge filters still containing traces of solvent. Leakage of solvents and leakage of ozone-damaging refrigeration gases are further risks specific to dry cleaning.
In recent years, the industry has responded with less-toxic alternatives to perchloroethylene, including hydrocarbons (EcoSolv™ drycleaning fluid from CPChem) and glycol ethers. One glycol ether, dipropylene glycol n-propyl ether (DPnP), has been used in combination with other components like polysulfonic acid (U.S. Pat. Nos. 6,086,634; and 6,036,727). Another allegedly environmentally friendly alternative to perchloroethylene is available from GreenEarth. Cleaning, using a cyclic siloxane optionally in combination with a glycol ether (U.S. Pat. Nos. 6,042,617 and 6,063,135). While they do have lower toxicity, siloxanes have relatively low cleaning power and are preferably avoided. Other glycol ethers have been recommended for use in dry cleaning, more particularly propylene glycol tert-butyl ether (PTB), propylene glycol n-butyl ether (PNB), dipropylene glycol tert-butyl ether (DPTB) and dipropylene glycol n-butyl ether (DPNB) (U.S. Pat. Nos. 5,888,250; 6,156,074; 6,273,919 and 6,350,287 from Rynex Holdings Ltd.). Use of glycol ethers represents a significant step toward replacing perchloroethylene in dry cleaning, but the industry continues to need a better replacement for it.
Solvent-based dry cleaning processes present several limits and/or disadvantages compared to wet cleaning:
While solvent-based dry cleaning processes are quite effective for removing oily soils and stains, they are not optimal for removing particulates such as clay soils or the water-soluble stains such as the sugars, commonly found in many fruit drinks and carbonated beverages; it may also require special treatment conditions to remove proteinaceous stains.
Traditional dry cleaning involves energy intensive processes consuming approximately 40%. more energy than traditional wet cleaning and consuming more water in the dry cleaning process for an equal poundage of garments cleaned.
Moreover, dry cleaning equipments are substantially more capital intensive compared to wet cleaning equipments. It also compares unfavourably as to the operating costs, and specifically with regard to solvent sludge and filter removal requirement, higher repair and maintenance costs due to higher technical complexity and higher consumption of energy and water.
Wet Cleaning
Wet cleaning is a non-toxic, environmentally safe alternative to dry cleaning, utilizing computer-controlled washing machines, biodegradable soaps and conditioners, and various types of pressing equipment that may be specialized for many different fabric and fiber types. Modern wet-cleaning technology was developed by Miele in early 1990s and involves the use of water as solvent instead of organic solvents. Water usage as a solvent offers several advantages:                Approximatively 98%. of all stains are water-soluble or can be carried away by water.        Water is able to clean almost all textiles and leathers except certain textiles with water-soluble coatings.        Cleaning quality of water is superior to any traditional solvent, by removing stains rather than spreading.        
The wet cleaning process in a professional wet cleaning operation is similar to washing garments in a modern household washing machine, albeit in a controlled environment regarding to speed, temperature and water volumes. Professional wet cleaning operations require specially designed equipment such as wet cleaning machines and dryers.
Compared to dry cleaning, professional wet cleaning equipment is easier to operate and maintain because of lower technical complexity; it also requires considerably less pre-spotting because most stains are water-soluble. Nevertheless, wet cleaning process require moderately more sorting prior to cleaning because of more delicate cleaning and also moderately more finishing time.
Even if the quality of wet cleaning has improved since the early 1990s, modern wet cleaning compositions and methods still provoke damage to garments in form of color loss and dimensional changes like shrinkages.
In the traditional water-based washing process, dimensional changes and color loss are the results of water penetrating into the cavities of the fibers and during the drying process in a tumbler evaporation of water, of water creating access of pressure resulting in damage to the protein fibers.
Then, to avoid or reduce a potential shrinkage effect, cleaning is conducted in low water temperature with poor cleaning results particularly regarding oil and oil-soluble stains that, consequently, can not be removed.
Several prior art systems have been proposed for wet cleaning of clothing that is conventionally dry cleaned:
U.S. Pat. No. 5,634,947 discloses a wet cleaning system that uses a solvent of propylene glycol monomethyl ether containing 4% to 50% by volume of water.
WO 98/56975 teaches a shrinkage prevention agent that contains at least one organic acid, with terpene and phenol of plant origin as its effective components. Amongst organic acids acetic acid is listed with cyclotene, 2-cyclopentenone, para-cresol, meta-cresol, orthocresol, furfural alcohol and guaiacol, in addition to other components in trace amounts. The anti-shrinkage agent is used as 0.01-0.05 parts by volume per 100 parts of regular water.
Process and compositions for wet cleaning of delicate garments with minimal wrinkling, shrinkage and color damage have been proposed in U.S. Pat. No. 6,139,587 using a method involving soaking of the garments in a certain type of surfactant-containing aqueous solution under specific conditions requiring five different steps.
However, after this wet-cleaning process, the garments are typically hanged to dry in the open air overnight. Then, to soften the fibers which generally stick together and create a “rough” surface, garments are subsequently tumbled cold. To avoid this roughness, wet cleaners typically either add cationic surfactants (softeners) during the last rinse of the washing cycle, thereby coating the garments against sticking, or put the dry garments into the garments dryer to soften them mechanically.
Household
CA 2,531,324 addresses the question of laundering processes of sensitive garments in a conventional home washing machine. The use of aqueous laundering process in a conventional washing machine is considerably more convenient and inexpensive than virtually any other laundering method, but can produce inacceptable results when applied to a broad range of delicate or dry-clean only garments. The system in CA 2,531,324 uses a flexible polymer wrap container to avoid abrasion and stress that severely damage the garments.
Specially formulated household washing products may be purchased for the washing of sensitive garments. However, similar to modern wet cleaning, this still requires the garments to be hanged to dry which typically still provokes stickiness of the fibers, creating a rough garment surface. The use of softeners results in residues and leaves a “greasy” texture.
Traditionally, wet cleaning operations could not compete with dry cleaning due to the lack of process and technology not allowing all garments to be cleaned in water and finished in a similar time frame.
Given the foregoing, there is clearly a continuing and ongoing need to develop simple, aqueous laundering compositions and procedures to clean delicate garments and strike an appropriate balance between effective stain and soil removal, and avoided fabric damages, dimensional changes and color loss.
This is an object of the present invention to avoid well-known drawbacks associated to classical dry cleaning and wet cleaning alternatives of sensitive garments and to propose efficient and simple solutions for their wet cleaning and drying in professional or household equipment without any dimensional changes, shrinkage, surface damages, dye or color loss.